St. Ildephonsus was the Archbishop of Toledo, and died 23 January, 667. He was born of a distinguished family and was the nephew of St. Eugenius, his predecessor in the See of Toledo. At an early age, despite the determined opposition of his father, he embraced the monastic life in the monastery of Agli, near Toledo. He was ordained a deacon, around the year 630. He was called by King Reccesvinth, near the end of 657 to fill the archiepiscopal throne of Toledo, where he governed the Church of Toledo for just over nine years and was buried in the Basilica of Saint Leocadia.

Ildephonsus had a strong devotion to the Blessd Mother, and it is said that one day he was praying before the relics of Saint Leocadia, when the martyr arose from her tomb and thanked the saint for the devotion he showed towards the Mother of God. It was also related that on another occasion the Blessed Virgin appeared to him in person and presented him with a priestly vestment, to reward him for his zeal in honoring her.

The literary work of Ildephonsus is more widely known than the details of his life, and merits for him a distinguished place in the role of Spanish writers.